Nowcast/Forecast System of Prince William Sound,

Alaska(PWS-NFS)

INKWEON BANGCHRISTOPHER N.K. MOOERS

OCEAN PREDICTION EXPERIMENTAL LABORATORY (OPEL)

RSMAS, UNIVERSITY OF MIAMIMIAMI, FLORIDA, USA

Outline

• Introduction• PWS-NFS with NDBC Wind• PWS-NFS with PWS-RAMS Wind• Process and Validation Studies• Challenges

Offshore Circulation

Aleutian Low

L

Alaska Current (EBC) & Alaska Stream (WBC)Alaska Coastal Current

Throughflow - ACCWind - Aleutian LowBuoyancy - SnowmeltTideTopography - Fjord

Forcings

Prince William Sound

Barotropic – Flat Bottom

Barotropic – Realistic Bottom

Baroclinic – Realistic Bottom

•Forcing•Verification•Data assimilation

CurrentTemperatureSalinityParticle trajectories

•CTD, ADCP, etc•UAF, SEA,OSRI

Historical Data Sub-

Models• Tide• Freshwater Flux

Real-Time Observing

System• Winds, SST, Sea Level• NDBC, NCEP, NOS

Fisheries

Model

Ecosystem Model

OSCAR(chemical

fates)

Web

Archives

PWS-POM

Horizontal Maps

TransectsTime seriesAnimations

Atmospheric Model

• Wind, Heat Flux• Precipitation, SLP

Model Domain andLocations of Observations by NDBC, NOS, PWSSC

Attributes of PWS-POM

• North of HE & MS expand to NGOA (North of 59oN, 150oW ~ 145oW)

• 0.01o 0.02o (~1.1 km) 15 levels more vertical levels (26 levels)

• External timestep = 5 seconds, Internal timestep = 2.5 minutes

• HORCON = 0.2, TPRNI=1.0 HORCON = 0.1, TPRNI=0.2 • Maximum depth = 500 m full depth • Climatological T/S at open boundary from a larger domain

model (Global NCOM)• Radiation boundary condition at open boundary• Mellor-Yamada 2.5 vertical turbulence closure scheme• Smagorinsky horizontal turbulence closure scheme

Attributes of PWS-NFS

• Since November 2000• Hourly wind (NDBC 46060) high-resolution (4 km) regional

atmospheric forecast model (PWS-RAMS)• 8 Tidal constituents (O1,K1,P1,Q1,M2,S2,N2,K2) plus ACC transport • Monthly heat flux (COADS) PWS-RAMS• Daily, non-uniform climatological freshwater flux (hydrological

model) forecast from hydrological sub-model and/or PWS-RAMS• Everyday 24-hour nowcast

48-hour forecast without wind 72-hour forecast (PWS-RAMS)• Automated download of near-realtime observational data (wind, sea

level, water temperature)• Output to website in graphic/tabular format

• http://pws-nfs-osri.rsmas.miami.edu

Comparison of Obs/Sim Water Temperatures at three locations

Sea Level at Valdez(barometric pressure compensated)

PWS-NFS with RAMS wind• Since March 17, 2003• Same configuration as PWS-NFS with NDBC wind• RAMS wind field is uploaded everyday to UM from UAA• 1-hour interval, 36-hour forecast• Converted to 10 m height and interpolated onto model

grid• Run with RAMS wind field for 3 days (past 24-hour

RAMS + 36-hour RAMS forecast)• Post results at web• Archive RAMS wind (first 24 hours for next day forcing

and comparison)• Comparison plots at NDBC locations (at 5 m height)• Display 3-hour interval RAMS wind field

Some Attributes OF PWS-RAMS

(Operated AT AEFF, UAA)

 

• VERSION 4.3, NON-HYDROSTATIC

• TRIPLY NESTED (HORIZONTALLY) PARENT GRID (50 X 50); DX,Y = 64 KM; (3200 KM X 3200 KM) SECOND GRID (70 X 58); DX,Y = 16 KM; (1120 KM X 928 KM) FINE GRID (102 X 82): DX,Y = 4 KM; (408 KM X 328 KM)

 • VERTICAL COORDINATE IS STRETCHED SIGMA

36 GRID POINTS INITIAL DELTA_Z 50 M STRETCHING FACTOR IS 1.13 MAXIMUM GRID SIZE IS 1 KM

 • INITIALIZATION FROM NCEP ETA MODEL 

INITIAL ANALYSIS & FORECAST FROM 12Z OPERATIONAL RUN PROVIDES 3-DAY INITIALIZATION & TIME-VARYING BOUNDARY CONDITONS

 

• http://aeff.uaa.alaska.edu/

RAMS vs NDBC at 46060

NDBC RAMS

RAMS WIND

Comparison of Obs/Sim Water Temperatures at three locations

Comparison of Obs/Sim Sea Level at Valdez

Validation Experiment• Seasonal Cycle of 1996 (SEA)• Hourly Wind (NDBC 46060)• Monthly Heat Flux (COADS)• Short Wave Radiation (COADS Cloud Cover)• Monthly Freshwater Flux (Hydrological Model)• 0.01o 0.02o (~1.1 km) 15 levels• 1995~1997 ADCP Mooring near HE• Mellor-Yamada 2.5 Turbulence Closure Scheme• HORCON=0.1, TPRNI=0.2, Water Type=III• Three Cases depending on velocity condition at open

boundary Case 1 - Daily Velocity ProfileCase 2 - Daily TransportCase 3 - Monthly Transport

Winds, Heat/Freshwater Flux, and Mean transport

ADCP Mooring at HE

Velocity Profile

Observed Monthly Transport

Daily Transport

Velocity at ADCP mooring (Velocity Profile case)

Mean Velocity Profile and Standard Deviation

Temperature Comparison at CLAB in 1996

Monthly Transport

Daily Transport

Observed

Velocity Profile

Mean Temperature Profile and Standard Deviation

Temperature and Salinity at CFOS13April

June

Sept.

Dec.

Simulated T balance inside PWS

Decomposition of T/S advection [RIGHT COLUMN: T = S]

• Extended PWS (EPWS)-NFS and link to a larger domain model (Global NCOM)

• Coupling with PWS-RAMS – heat flux, E-P, etc.

• Forecast freshwater flux using the hydrological model and PWS-RAMS

• Link to ecosystem model• Add a wave model

Challenges

Hydrological Model (Simmons 1996)

• Watersheds (289) are delineated based on digital elevation model

• Model is driven by climatological daily air temperature and precipitation and considers variations in elevation and glacier distribution

• 241 watersheds inside PWS-NFS domain are used (since12 MAR03)

Daily freshwater discharge through precipitation and land discharge

• Daily, non-uniform land discharge along coastline • Precipitation is applied uniformly to all grid points

Spatial distribution of annual land discharge (m3)